Aug 19, 2010

4-20mA Signal Generator (AT89C2051)

Simply a 0-24 mA signal generator using AT89C2051/4051, PCD8544 monochrome LCD (was used for N5110 phone), DAC7611 (12-bit 1-ch  DAC), TL494 (commonly used in switch mode power supply).




How it works:
LCD and push buttons are the user interface. Select the step 1mA or 4mA, then press increase or decrease. MCU send the value 0-2500 to DAC and convert it to 0-2.5V. This voltage is reference voltage for the TL494. TL494 work as pulse width controller which sense voltage at the shunt resistor, in fact it works as current regulator instead of voltage regulator. 24VDC is generated by B0524LS-1W able to convert 3.3-5.5VDC to 24VDC/1W. You can add selection switch at the mA output so the generator can function external/internal power mode. The mA out is short circuit-proof in internal power mode. This circuit is designed to run on battery. If you have 24VDC source, DC/DC converter is not necessary to use but make sure the 24VDC source is isolated from the other system.
The source code can be viewed here https://docs.google.com/file/d/0Bz15eKH_erJrbkRrY1FFRzU2ZVE/edit

16 comments:

Anonymous said...

Helo! It's very good! I need one. Sorry , my bad english. I interested in more information about how to build one of these myself. Please write to the ymun@freemail.hu. Thank You.

Anonymous said...

helo how can i build the project 4-20 ma my email is tzagge@yahoo.gr thank you

Anonymous said...

This is a very great tool. If you have instructions, can you send it to cowardsavior@yahoo.com?

Thank you very much

Anonymous said...

Hello,

I'm also looking for a DIY instruction. Can you send it to jim.guyco@gmail.com?

Thank you!

Anonymous said...

Hi there, this looks great, do you have any other instructions besides the diagram? If not i can probably manage with that. My email is sam.guy@pmcontrol.com.au
Thanks,
Sam.

Silvester Dao said...

What kind of information do you all need? Simply create the circuit, create the program and compile it and download to microcontroller.

Anonymous said...

People are probably looking for the program source code.....a counter from 0 to 2500

Anonymous said...

Hello.
Could you give me the schematic connect buttons to GND and the hex codes for Atmel? Thank you! My email is ch66ti@meta.ua
Thanks,
Amit.

Well Smith said...

hi,i want souce code ( c or assembly)
wellloso@gmail.com

Silvester Dao said...

you can see on my post 23 jan.

Anonymous said...

Any chance that I can purchase one already made from you?

okrauth@gmail.com

Silvester Dao said...

No. I am busy at the moment.

Heinrich Baumann said...

very creative design maybe you can sell it to these guys http://www.divize.com/current-loop.html ;-)

Asd said...

Helo! It's very good! I need one. Sorry , my bad english. I interested in more information about how to build one of these myself. Please write to the javxaa1676@yahoo.com.Please please please...

Anonymous said...

Hello sir,
instead of DAC7611 can i use MCP4921

Silvester Dao said...

I think it can, as the timing diagrams are similar. You can try.

Post a Comment

Water Level Sensor of Washing Machine (STM32F103C8T6)

Washing Machine Typical work principle of water level sensor of a washing machine shown on the picture. Sensor is located above the wa...